# How to "paint" a pedicle screw by hounsfield unit?

**URL:** <https://discourse.slicer.org/t/how-to-paint-a-pedicle-screw-by-hounsfield-unit/21185>\
**Category:** Development\
**Tags:** python\
**Created:** [December 22, 2021, 4:05pm UTC](https://discourse.slicer.org/t/how-to-paint-a-pedicle-screw-by-hounsfield-unit/21185 "2021-12-22T16:05:18Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![jumbojing](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/jumbojing/32/10811_2.png) [@jumbojing](https://discourse.slicer.org/u/jumbojing)\
**Post date:** [December 22, 2021, 4:05pm UTC](https://discourse.slicer.org/t/how-to-paint-a-pedicle-screw-by-hounsfield-unit/21185/1 "2021-12-22T16:05:18Z")

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How to “paint” a pedicle screw by hounsfield unit ?  
@lassoan@Juicy@jamesobutler @jcfr @pieper  
I want to “paint” a pedicle screw(a Cylinder in pedicle) by hounsfield unit , e.g. if a point in soft tissue is red ,elif in bone is blue.

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**Author:** ![jumbojing](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/jumbojing/32/10811_2.png) [@jumbojing](https://discourse.slicer.org/u/jumbojing)\
**Post date:** [December 22, 2021, 4:23pm UTC](https://discourse.slicer.org/t/how-to-paint-a-pedicle-screw-by-hounsfield-unit/21185/2 "2021-12-22T16:23:54Z")

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In the [PedicleScrewSimulator](https://github.com/lassoan/PedicleScrewSimulator/blob/7bf04fc00695115ac64742e692849a15e430f9dc/PedicleScrewSimulator/PedicleScrewSimulatorWizard/GradeStep.py#L281-L331) , grade the pedicle screws with the **probevolumewithmodel** , I don’t know if it is based on the HU value.

@lassoan  
@ungi

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**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [December 23, 2021, 5:47pm UTC](https://discourse.slicer.org/t/how-to-paint-a-pedicle-screw-by-hounsfield-unit/21185/3 "2021-12-23T17:47:07Z")

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Yes, Pedicle Screw Simulator extension paints the screws with the CT voxel values (in HU).